Fungal communities in biowaste composting: a comparative study of multiple ratios of woodchips vs. a...

The large production of biowaste can cause environmental risks if not managed properly. Composting is considered a sustainable solution for the disposal of this material, but generating high-quality compost requires proper design of feedstock composition and operational procedures. Microorganisms mediate the degradation of organic matter into a nutrient-rich substrate yet their response to different compost recipes is still poorly understood. In this study, fruit and vegetable biowaste was co-composted with woodchips or a perlite + cardboard mix in four different recipes (two representing optimal composting conditions and the other two were unideal composting conditions). Then, using Illumina high throughput sequencing, was defined the core fungal community shared by all treatments, mapped fungal succession through all composting phases and treatments, and identified indicator taxa associated to compost's specific recipes or phases. Our results confirm the presence of a core microbiome common to all compost piles dominated by Aspergillus but also reveal that every recipe has a degree of uniqueness in its fungal community and that the type of bulking agent used can significantly affect the composition of the fungal community during the latest stages of composting. At least one biomarker was associated with every recipe, with some reflecting the environmental conditions occurring such as the yeast P. kudriavzevii when more biowaste was present or T. lanuginosus when higher temperatures were reached during the thermophilic phase. These findings will contribute to increasing the knowledge of microbial dynamics during composting and provide useful information for the future use of biological parameters to assess compost quality.